Evaluation of a rate-adjusted area under the curve method to reduce the
impact of variability in bioequivalence testing
Abstract
Aim: To quantify the utility of the rate-adjusted area under the
concentration curve method in increasing the probability of a correct
and conclusive outcome of a bioequivalence (BE) trial for highly
variable drugs when clearance (CL) varies more than volume of
distribution (V). Methods. Data from a large population of subjects were
generated with variability in CL and V parameters and used to simulate a
two-period, crossover BE trial. The 90% confidence interval for
formulation comparison was determined following BE assessment using the
area under the concentration curve (AUC) ratio test, and the proposed
rate-adjusted AUC ratio method. An outcome of bioequivalent,
non-bioequivalent or inconclusive was then assigned in relation to
predefined BE limits. Results: We illustrate the utility of the
rate-adjusted AUC method for BE testing when CL varies more than V. The
approach is expected to enhance the probability of correctly assigning
BE or non-BE and to increase study power to further reduce the risk of
an inconclusive trial. Conclusions: The rate-adjusted AUC method
represents a simple and readily applicable approach to enhance the BE
assessment of drug products when CL varies more than V.